What Is an American Polydactyl, and Is Extra Toes a Breed or a Trait?

An American Polydactyl is a cat with extra toes. The name describes the toes alone: no registry keeps a standard or issues a pedigree under it.

Polydactyly is caused by a dominant mutation in a stretch of DNA called the ZRS, which switches on a limb-building gene, sonic hedgehog, in the growing paw. One copy from one parent is enough to produce extra toes, which is why the trait runs in families of cats.

The mutation can appear in any domestic cat population, any breed and any colour.

What Does Polydactyly Actually Look Like?

A polydactyl cat typically has six or seven toes on one or more paws instead of the standard five (front) or four (rear). The extra digits are usually on the inside of the paw, so the foot looks broader and mitt-like.

The degree varies from cat to cat. Some have one extra toe on one paw, and others have extra toes on all four feet. In the Hemingway cats studied by Lettice and colleagues, about four in five affected cats had extra toes on the front paws only, while one of the British variants in the same study affected all four paws.

Polydactyl cats are especially familiar along the North American Atlantic coast, and popular accounts tie them to ships' cats and port towns. The best-known colony lives at the Ernest Hemingway Home and Museum in Key West, Florida: about forty cats descended from one polydactyl founder given to Hemingway in the 1930s, roughly half of them with extra toes.

Why Is This a Trait and Not a Breed?

No major registry recognises "American Polydactyl" as a breed. TICA, CFA and FIFe do not list it.

Most breed standards treat polydactyly as a disqualification.

The best-known exception is the Pixie-Bob, whose TICA standard permits polydactyly up to seven toes per paw. That allowance belongs to the Pixie-Bob standard, so it gives a polydactyl cat of any other background no breed status.

Registry recognition as a breed

None

Best-known standard that permits it

Pixie-Bob (TICA), up to seven toes per paw

Inheritance

Autosomal dominant; one copy produces extra toes

Where it turns up

Worldwide, and especially familiar on the North American Atlantic coast

What it affects

Toe count and paw shape

What it does not affect

Coat, body type, temperament or size, and no wider health effect has been described

What Care Does Polydactyly Require?

The extra toes change one thing about daily care: nail monitoring.

An additional toe that does not contact the ground may not wear its nail naturally. Without regular trimming, the nail can curve and grow into the pad, causing pain and infection.

The extra digits that sit higher on the paw, or tucked between other toes, are the nails most easily missed, and a nail that has started to curve toward the pad is already overdue for a trim.

Beyond nail care, a polydactyl cat has the same needs as any domestic cat. The researchers who identified the Hemingway mutation concluded that this type of polydactyly has no further effect on a cat's health, reasoning from people with the same class of mutation, in whom it changes the hands and feet and nothing else. Temperament, activity and lifespan follow the individual cat and its background.

How Do You Evaluate a Cat Described as an American Polydactyl?

A cat sold under this name is a domestic cat with extra toes, so the useful checks are the ones you would make on any cat, plus a look at the extra nails.

• Count the toes and check each extra nail for curve, pad contact and condition
• A price set for a domestic cat, with no premium for the toes
• Assess the cat's actual temperament, health and coat on their own merits
• Any rarity or value claim traced to a registry, bearing in mind that none lists the name